there is one DNA mutation per lung cell for every 50 cigarettes smoked, according to a new analysis. People who smoke a pack of 20 a day for a year generate 150 mutations per lung cell, 97 per larynx cell, 39 per pharynx cell, 18 per bladder cell and six per liver cell.
Epidemiological studies previously linked tobacco smoking with at least 17 classes of cancer, but this is the first time researchers have been able to quantify the molecular damage inflicted on DNA.
Ludmil Alexandrov at Los Alamos National Laboratory in New Mexico and his colleagues achieved this by comparing tumour DNA from 2500 smokers and 1000 non-smokers. This allowed them to identify which mutations were associated with smoking.
Theoretically, every DNA mutation has the potential to trigger a cascade of genetic damage that causes cells to become cancerous. However, we still don’t know what the probability is of a single smoking-related DNA mutation turning into cancer, or which mutation types are likely to be more malignant. “This is research we are currently pursuing,” Alexandrov says.